Propeller



Aug. 23, 1938. s. HEATH 2,

' PROPELLER6 Filed April 23; 19530 6 Sheets-Sheet 1- Gttgrneg S. HEATH Aug. 23, 1938.

PROPELLER Filed April 23, 1930 6 Sheets-Sheet 2 Snnentor Ka i.

Aug. 23, 1938 S. HEATH PROPELLER Filed April 25, 1950 e Sheets-Sheet 3 Gttornegs S. HEATH Aug. 23, 1938. Q

PROPELLER Fild April 25, 1939 6 Sheets-Sheet 4 Snnentor' War, M

s. HEATH PROPELLER 6 sheets-sheet" 5 Filed April 2:5, 1930 i I i 1 "iia a illiIlII-llll II lllll iIlIIIIIlIIIIIl Zmventor S. HEATH,

Aug. 23, 1938.

PROPELLER Filed April 23, 1950.

6 Sheets-Sheet 6 Patented Aug. 23, 1938 UNITED} STATES- rnorcuna Spencer Heath, Elkridge, Md., assignor to The American Propeller Company, Baltimore, Md., a corporation of Maryland Application April 23, 1930, Serial No. 446,623

30 Claims.

ing it necessary forthe operator to carefullyv watch the indicating means to the end that fur-.

ther operation of the pitch varying means might 15 be discontinued when the pitch of the blades corresponded to that desired. This required careful and skillful operation on the part of the operator,

it being necessary for the latter to devote his entire attention to this operation and in many init was often impossible to disconnect the power from the pitch varying means at the proper instant when the pitch of the blades would correspond to that desired. It is accordingly one of the objects of the present invention to provide a novel controllable pitch propeller, so constructed as to avoid the above dimculties.

, Another object of the invention is to provide in a variable pitch propeller, the angularity of the blades of which may be varied during operation thereof, novelmeans for securing such change in angularity.

A further object is to provide, in combination with a variable pitch propeller, novel means for automatically varying the pitch of the blades during operation and in accordance with the will of the operator.

Another object is to provide, in a propeller of the above character, novel means capable of being adjusted to a desired pitch setting, in com- .bination with novel means for thereafter automatically' changing the pitch of the propeller blades in accordance with the said pitchsetting.

A further object is to provide a device of the above character embodying novel means fdr varying the pitch of the propeller blades during operation including manual power, power derived from the engine shaft which rotates the propeller, or

. power from an external source, any one of said power means being available for use during normal operation of the propeller. A

A still further object is to provide means for changing the pitch of the blades of a rotating propeller comprising a novel arrangement of parts so constructed to secure positive and eflicient stances due to the construction of the mechanism operation together with minimum weight, the

parts being assembled in a novel manner in order to obtain a compact arrangement capable of ready adaptability to aircraft.

Other objects and features of novelty will appear more fully hereinafter from the following detailed description when taken' 'in connection I with the accompanyingdrawings. It is to be expressly understood, however, that the drawings are for purposes of illustration only and are not designed as a definition of the limits of the invention, referencebeing' had for this purpose to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the several views, V

Fig. l is a vertical section, with parts broken away, of a propeller embodying the present invention; I

Fig. 2 is an end view of the mechanism illustrated in Fig. l;

Fig. 3 is a perspective of one form of pitch varyform of centrifugal clutch which may be used c e with the mechanism shown in Fig. 5;

Figs. 9, 10 and 11 are detailed views of the m dicating and control means which may be employed with the structure illustrated in Fig. 5;

Figs. 12, 13 and 14 are views illustrating a modified form of the indicating and control means shown in Fig. "5; and

Fig. 15 is a sectional view of a modified form of connection wherein the motor is directly connected with the pitch-changing mechanism.

Referring more particularly to Figs. 1 and 2, a shaft I3 is drivably connected to the crankshaft of an internal combustion engine, a portion oi. the engine crankcase being shown at H, and carries a split propeller hub 15 of suitable construction, the-said hub carrying a plurality of blades 16 adapted to propel an aircraft when rotated by the huband shaft. The hub i5 is drlvably secured tothe shaft by cooperating splines ll, I8

and is maintained in proper relation thereon by means of an outer split cone l9 and lock nut. 20, the latter being effective to force the inner bevelledface 2| of the hub into firm engagement with the outer bevelled face 22 of a sleeve 23 carried by the drive shaft. p

As shown, the roots of blades l6 are provided with a split lagging 24 the inner end of which is threaded into a socket or ferrule 25, the outer peripheral portion of said lagging being secured to the socket by means of a plurality of set screws 26. In order, to rotatably support the socket 25 within the hub, a suitable thr'ust bearing v2'l is interposed between a collar 28, threaded within propeller.

the hub, and a peripheral flange 29 formed on the inner end of the socket, the bevelled portion 36 of said flange cooperating with face 3| of the hub to constitute a bearing surface.

Means are provided to rotate the blades with respect to' the hub in order to vary the pitch of said blades, and preferably said means are constituted in amanner to enable the pitch of the blades to be changed during operation of the In the form shown, a pair of sleeves 32 and 33, rotatable with respect to eachother, are concentrically arranged with respect to the sleeve 23, the inner sleeve 32 being free to-rotate on sleeve 23. Suitably secured to sleeve 32, at either end thereof are gears 34 and 35, a similar pair of gears 36 and 31 being attached to or formed integrally with the sleeve 33. A pair of shafts 38 and 39, Figs, 2and 6, located in each end of the hub and rotatably supported therein in any suitable manner, carry on their inner ends exteriorly of the hub, gears 46 and 4| respectively, in mesh with each other and with gears and 31. Each of the shafts 38 and 39 carries intermediate its ends and within the hub, a worm 42 and 43, between which there is located, a worm wheel 44, suitably journaled in the hub and in mesh with each worm. A sun pinion 45, which may be formed integrally with the worm wheel 44, is adapted to engage a pair of planetary gears 46 and 41, rotatably carried by stub shafts 48 and '49 that are fixedly mounted in the bottom of socket 25; the' said planetary gears being also in engagement with an internal gear 50 fixed within pinion 45 in a direction determined by the direction of rotation of gears and 4|. The planetary gears 46 and 41 cooperate with the internal stationary gear 56 to impart a turning movement to the propeller blades through the hub 25 and lagging 24 to vary the angularity or pitch of the said blades. It is here pointed out that the pitch of the threads of each of the worms 42 and 43 is such that there will be no tendency of the shafts 38 and 39 torotate by reason of any-thrust or turning force applied to the propeller blades.

In Fig. 4, there is illustrated, an alternative form of the,invention, which is similar to that shown in Fig. 1 in all respects except the planetary reduction gearing housed within the propeller hub. As shown, the planetary gears 46 and 41, in this form, are compounded, that, is,

.each of these gears is formed integrally with a gear ratio from that utilized in the structure 11-- lustrated in Fig. 1, without materially altering the arrangement of parts.

Normally, the sleeves 32 and 33 carrying gears 35 and 31, which are in constant engagement with gears 40 and 4|, rotate with the driving shaft.

- In order to impart motion between these sleeves,

of the propeller blades through the system of reduction gearing above set forth.

Means other than the brake bands 55 and 56, are provided for operating the pitch varying mechanism heretofore described, and preferably such other means are constructed in such a manner. as to be operable not only when the propeller is rotating, but also when the propeller is stationary. To this end, a spider 58 which is r0- tatably supported by the sleeve .32, as by means of ball bearings 59, carries a pair of shafts 60 and BI, the ends of each of said shafts rotatably carrying planetary gears 62 and 63, Figs. 1 and 3. The gears 62 mesh with the gear 36 and also with an internal ring gear 64, while gears 63 mesh with the gear 34 and a similar internal ring gear 65. Each of these ring gears isrotatably supported with respect to a casing 66, fixed in any suitable manner as by means of screws .67 to the crankcase I 4, and carry external ring gears 68 and 69 which mesh with pinions l6 and II respectively. Each of these pinions preferably engages the other the teeth thereof being partially overlapped for this purpose, the said pinions being keyed to shafts l2 and 13, Figs. 2 and 3,

which shafts are suitably journaled in the walls of the casing 66.

The shaft 13, as shown, is'extended in order that manual or power means may be applied thereto in order to change the pitch of the propeller blades. Normally, the shaft 13. is atv rest, 5

whether the propeller is in operation or whether the same is idle. It will be seen that rotation of shaft 13 in either direction will rotate pinions I6 and H in opposite directions which will, in turn,-drive the external ring gears 68 and 69 also in opposite directions. The planetary gears 62 and 63 ,will likewise rotate in opposite directions with respect to each other, through the oppositely rotating gears 64 and 65, to cause relative movement of sleeves 32 and 33 to thereby alter the pitch of the propeller blades, the change in pitch being directly proportional to the extent of movement of the normally stationary shaft 13.

Power means may be provided for rotating the normally stationary shaft 13 in order to change the pitch of the propeller blades in the manner indicated above. In the form shown, such means preferably comprises an electric motor 14, fixed to any suitable stationary portion of the aircraft and which may be provided with a hollow armature shaft 15 through which the extended shaft I 13 extends, a bearing member 13 being provided for rotatably supporting the said extended shaft adjacent its inner end. The armature shaft is normally disconnected from .the shaft 13, a drive able connection therebetween being effected by means responsive to the speed of the motor,

'As shown, Figs. 7 and 8, the speed-responsive amass-r shoes I8. Each of these shoes is provided with a headed pin I9 passing through the perforation in each of the said lugs, and resiliently urged inwardly, as by means of springs 80 in order to maintain the clutch shoes I8 normally in retracted position. Upon rotation of shaft I5, the clutch shoes will, at a certain speed, be effective to frictionally grip the rim 8|. of a driven element82, suitably secured to the shaft I3. It is here point- -ed out that this centrifvgally actuated clutch enables the motor to be brought up to speed substantially free of any load. In addition to this.

feature, the motor is normally disconnected from the shaft I3 thus relieving the said shaft of unnecessary load when it is desired to vary the pitch of the propeller blades by operation of the brake drums 53 and 54 as heretofore described.

However, in certain instances, it may be desirable to eliminate the clutch 'I8,*8I, in which event the motor shaft I5 is directly connected to shaft 13 as illustrated in Fig. 15.

Instead of employing the electric motor for rotating the shaft I3, manual means may be provided, such means being also preferably normally disengaged from the-said shaft. In the. form of the invention illustrated, Fig. 5, the manual means comprises a shaft 83 suitably journaled in a panel 84 and bearing member 85, and carrying a gear 86 at its outer end normally dis-.

-engaged with respect to, but movable into engagement with a gear 81 fixed to shaft I3. A

hand crank 88 is connected to the inner end of the shaft 83 in order to manually turn the same.

A spring 89 normally maintains the parts in the 1 position shown in the drawings.

Means may be provided for controlling the operation of the electric motor and for indicating the pitch of the propeller blades as altered by said motor, and preferably such means is'so constituted that the motormay be automatically disconnected from the pitch changing mechanism when the pitch of the blades has reached a value as predetermined by a prior adjustment of the indicating means. .To this end, a hollow shaft 90, suitably supported in bearing member 9| and insulating panel 92, is suitably geared to shaft I3 ina manner such that a one-degree change in pitch ofv the propeller blades will preferably rotate the shaft 90 an angular distance of two degrees.-

In order to drivabiy connect the shafts 'I3 and 90 in the manner indicated above, a combined bevel and spur gear 93 and a combined sprocket wheel and spur gear 94 are rotatablymounted on shaft 90 but drivabiy connected together through differential'pinions 95 carried by a spider 96, the latter being secured to the said shaft by any suitable means. The members 93- and 94 are driven by a pinion 91 and sprocket 08 each of which is fixed on shaft I3. The ratios .be-

tween the gear drive and sprocket drive are slightly different, hence members 93 and 94 will rotate at unequal speeds and impart a slow, differential motion to the shaft 90 through-the pinions 95 and spider 98.

' Remote from, the propeller, and in convenient reach of the operator there may be provided a combined indicating and remote control member indicated generally at 99, suitably journaled in the panel 84 and carrying a pointer I adapted to cooperate with a scale IOI suitably graduated in degrees. The member 99 also carries, on the opposite side ofthe panel, an insulating disk I02 constituting a switch member which is provided with slots I03 and I04, Figs. and 11, adapted to receive resilient contact strips I05 and I06 respectively. A second insulating disk I01, constituting a second switch member, is

carried by the shaft 90, Figs. 5 and 10, and is provided with a pair of arcuate shaped terminal members I08 and I09, a central terminal H0 and a continuous circular terminal III arranged the propeller blades is zero, then the gaps H2.--

and H3 will register with the ends of said contact strips and there will be no current flow to the motor, the scale then indicating the true pitch of the blades.

The electric motor I0 -is electrically connected with the switch member I01 and is connected in such a manner thatthe rotation of the motor may be reversed, if desired, whereby the pitch of the propeller blades may be reversed. A switch is preferably inserted in the energy supply circult for the motor in order to facilitate the control of the pitch changing operation. As shown, terminals I and H5 of the motor are connected to terminals 0 and I I I, Figs. 5 and 10, while a source of energy, such as for example, a batteryllii isconnected by leads III and H8 to the contact members I08 and I09, a control switch H9 being interposed in series with lead H8. The switch H9, as shown, is also adapted to rotate the control member 90 through a train of gearing comprising a pinion I20, fixed to the shaft of the push switch, an idler pinion I2I and an external gear I22 fixed to the periphery of 'the control member 99, in order to set the said control member at a desired pitch setting. Asshown, in Fig. 11, the external gear I22 is provided. with teeth on only a portion of its peripheryiin order to provide suitable stop means for the indicator pointer I00.

When it is desired to vary the pitch of the propeller blades by means of the electric motor 14,- the combined pitch setting and switch member H9 is rotated until the pointer I00 indicates the pitch or angularity thatthe blades are to automatically assume. Thereafter, it is only necessary to push the switch member H9 inclosureof switch I I0, there will be completed an electrical circuit from battery IIG, lead I" to the terminal I08 through the contact strip I03 to the central terminal IIO, motor terminals H4 and ,I I5 to circular contact member III, contact strip I06, terminal I09 and back to the battery by return lead H8 and closed switch H9. Substantially simultaneously with the closing of the last named switch and completion of the electrical circuit above outlined, the rotation of the motor 14 will establish by means "of the centrifugal clutch, a driving connection between the armature shaft 15 and the normally stationary shaft 13 whereby the latter will be rotated, and through the pitch changing mechanism heretofore described, including gears 10 and 1|, Fig. 5, the angularity of the blades will be altered.

As shaft 13 rotates, the switch member I01 carried by shaft 00 will also rotate an angular distance proportional. to the change in pitch, as heretofore described, until the gaps H2 and II3, Fig. 10, rotate to such a position as to receive the outer extremities of contact strips I05 and I06, whereby the current supply to the motor will be interrupted thus immediately decreasing the,

speed of the motor to cause the centrifugal clutch elements 18, Fig. 7, to become inoperative and to interrupt the driving connection between shafts 13 and 15. The angularity of the propeller blades will then correspond to the initial setting a of the control member 99 with its indicator I00 and associated dial IN. I

If it is desired to reverse the pitch of the propeller by the electricalmeans, the combined pitch setting and control member H9 is turned In the opposite direction to the desired reverse pitch setting, as indicated on the scale I00, and then depressed to complete the circuit through lead -I I8. The contact strip I05 now connects contacts 7 I09 and H0 while strip I05 bridges terminals I00 and III audit will thus be seen that the direction ,of current through the motor will be reversed. As before, the pitch of the blades will be altered to that indicated by pointer I00, and further change will be automatically arrested because of the interruption of the motor circuit by reason of the registry of slots or gaps H2 and H3 with the contact strips I05 and I05.

In order to prevent racing of the engine which drives the propeller when the blades of the latter are at or near their zero pitch condition, a cam I28 secured to shaft 90, Figs. 3 and 5, operates a pivoted lever I20 and a linkage I30 connected to a throttle control rod I3I in such a manner, that movement of the throttle rod is limited by the position of the cam. The said camis initially set in such a position that it limits the opening of the engine throttle only when the propelier blades are at very low pitch and permits lea'st opening'when they 'are at zero pitch.

In order to indicate the pitch of the blades at ;all times'to the operator, whether the pitch has been changed by operation of the brake band mechanism or the manual means heretofore described, there is provided a second pointer I23,

Fig. 5, adapted to cooperate with a scale I24 the said pointer being carried by a shaft I25 drivably connected with the shaft 90 through gears I20 and I21, the latter being carried by the rim of the switch member I01.

Figs. 12, 13 and 14 illustrate a modified form of the remote control member wherein the parts are so constructed that the indicating member may be employed to indicate thepitch of the blades to the operator at all times, irrespective of whether the electric motor brake band mechanism'or manual means are utilized to vary the pitch of the blades. Asshown, Fig. 14, a control member 90, is provided with a hollow shaft I35 suitably journaled in panel 84, and is adapted,

to receive a rod I36 on the inner end of which is pivoted a control stop I31. The opposite end of the rod is secured to a forked member I38 having end portions I39 and I40 housed in apertures HI and I42 in disk I02, Fig; 13. These end portions are operable to engage respectively re-- Normally, the'parts are maintained in the position shown in Fig. 14 by means of the pivoted stop I31 engaging the inner end of the shaft I35. In this position, a spring I45 is compressed between the member I38 and an interior portion of the shaft I35. It will be seen that with the parts thus arranged, the control member 99- may be operated to automatically control the electric motor 14 as heretofore described. However, if it is desired to employ the brake band mechanism or the manual means for changing the pitch of the blades, it is only necessary to move the outer extremity of the stop downwardly whereby the spring I45 will be effective to move the member I30 to the left as viewed in Fig. 14. If the end portions I38 and I 40 do not register with the recesses I43 and I44, the disk I02 may be rotated by rotation of pinion- I20 until such registry occurs whereby disks I02 and I01 will I be locked together and all movements of shaft 90 will be indicated on dial IOI. v

When it is desired to change the pitch of the blades by means other than the electric motor 14,

either 'the brake band 55 or 56 may be operated by suitable means to cause relative rotation between sleeves 32 and 33 while the propeller is rotating, as heretofore described, or the manual means including the crank 88 may be operated,

' either when the propeller is rotating or when idle.

In either case, the shaft 13 will be rotated an amount proportional to the change in pitch, which may be indicated in themanner described above.

It will be noted that if the combined pitch setting and control member H0 be first depressed before rotation of the pointer to a new pitch setting, if the outer extremities of strips I05 and I00 occupy the gaps H2 and rI I3, the circuit to the motor will be incomplete and the latter will not start. As soon, however, as the member H0 is turned in either direction, an electrical circuit through the motor will be established, as heretofore described, and the rotation of the motor will cause the openings H2 and H3 to follow every change in position of the strips I05 and I06. That is, the pitch of the propeller blades will follow every movement imparted to the pointer I00.

There is thus provided by the present invention a variable pitch propeller having novel means for securing the angular adjustment of the blades thereof during operation, such means including manual means, electrical means,- or means operable by power derlved from the engine shaft, any one of said means being adapted to selectively vary the propeller pitch through a train of suitable gearing. The arrangement of the reduction gearing within the propeller hub and the location of the actuating mechanism externally of said hub is such that the mechanism may be readily adapted to existing types of aviation engines where compactness and economy in space amass:

is a prime requisite. By employing the novel indicating and control means for predeterminin the effective operation of the electrical means for varying the propeller pitch, an automatic opersuch use but may be employed wherever it is deto the form shown but may be embodied in varisired to propel a vessel through a fluid, medium.

Though there has been illustrated and described only one embodiment of the invention, it is to be understood that the same is not limited ous forms. For example, the electrical means for varying-the pitch of the blades may be omitted and suitable mechanical means such as a cam may be employed, constituting a control member selectively operable to a predetermined position and coacting with the brake-band-operated pitch changing mechanism for releasing the brake bands when the pitch of the blades corresponds with the setting of said cam control member. The speed responsive clutch for drivably connect ing the motor with the pitch changing mechanism may moreover be omitted and the motor directly connected to said mechanism, if desired.

.trol member.

While the indicating members Hi and 823, Fig. 5, have been illustrated as being spaced apart and provided with separate dials, the same could be concentrically arranged, if desired, by employingsuitable gearing, whereby both"indicating means may cooperate with the same scale and a compact and eflicient arrangement obtained. I

It is also to be understood that various other changes may be made in the construction and arrangement of the component parts constituting the invention without departing from the spirit thereof. Reference will therefore be had to the appended claims for a definition of the limits of the invention.

- What is claimed is:

1. In a controllable pitch propeller having a plurality of blades, a normally stationary control when the pitch of said blades-corresponds with the setting of said control member.

2. A controllable pitch propeller comprising a hub, driving means for said hub, a plurality of blades carried by said hub, means including an electric motor for changing the pitch of said,

blades while the propeller is being driven, a control member movable to any desired pitch setting, means for thereafter energizing said motor, and means coacting with said control member for automatically arresting movement of said pitch-changing means when the pitch of said blades corresponds with the position of said con- 3. A controllable pitch propeller comprising a hub, means for rotating said hub, a plurality of blades carried by said hub, a'control member manually movable only, said member being movable to any desired position during rotation of the propeller and means operable at the will of the operator for thereafter automatically changing the pitch of said propeller blades in accordance with the setting of said control member.

4. A variable pitch propeller having a hub,

means for rotating said hub, a plurality of blades carried by said hub, means including an electric motor for changing the pitch of said blades during rotation, and combined indicating and control means for said motor movable to indicate the desired pitch, separate means for thereafter rendering said motor operable, and means for automatically rendering said motor inoperative when the pitch of said blades corresponds to that indicated by the combined indicating and controlmeans.

5. A controllable pitch propeller comprising a hub, means for rotating said hub, a plurality of blades carried by said hub, a control member movable to any desired position during rotation of the propeller and electric power means includ ing a second control member for thereafter automatically varying the pitch of said rotating blades in accordance with the setting of said first named control member, said last named means being deenergized when the pitch of the blades corresponds to the setting of the first named control member 6. In a controllable pitch propeller, having a plurality of blades, a control member manually movable only, said member being movable to a desired pitch setting while the propeller is rotating, and. means" for thereafter varying the pitch of said rotatingblades at will, said means including a member coacting with said control member for automatically discontinuing the operation of said pitch varying means when the pitch of said blades corresponds with the setting to a desired pitch setting while the propeller is I rotating, means for thereafter varying the pitch of said rotating blades at will without moving said control member, and means for rendering I said first named means inoperative when the pitch of said blades corresponds with the settin of said control member.

8. A variable pitch propeller having in combination, a hub, means for rotating said hub, a

plurality of blades carried by said hub, mechanism for changing the pitch of said blades while the propeller is rotating including a normally stationary shaft, an electric motor normally disconnected :from said shaft, means for energizing said electric motor, and speed responsive means for drivably connecting said electric motor and said stationary shaft to thereby change the pitch of said blades.

9. A controllable pitch propeller comprising a hub, means for rotating said hub, a plurality of blades connected with saidhub, means for varying the pitch of said blades while the propeller is rotating including a normally, stationary shaft,

motor and shaft, a control member for predeter the blades of which is variable during operation tion of the propeller, means including gearing, operable to vary the pitch of said blades, an electric motor normally disconnected from said pitch varying means, means for energizing said motor, centrifugally actuated means for drivably connecting said motor and said pitch varying means, and means for deenergizing said motor.

11. A variable pitch propeller comprising in combination a plurality of rotatable blades, means including reduction gearing for varying the pitch of said blades during rotation thereof, an electric motor for actuating said pitch varying means and means drivably connected to said motor for automatically disconnecting said motor from said pitch varying means.

12. In a variable pitch propeller having a plurality of blades, means operable to vary the pitch of said blades during rotation of the propeller, an, electric motor for actuating said pitch varying means, means for deenergizing said motor when the pitch of said blades has reached a desired degree, and means for automatically disconnecting said motor from said pitch varying means upon deenergization of said motor.

13. In combination, a propeller having 'a pinrality of blades, means including an electric motor for varying the pitch of said propeller blades during the rotation thereof, means for energizing said motor, means actuated by rotation of said first named means for deenergizing said motor, said actuated means including a pre-set control member, and means for automatically disconnecting said motor and first named means when the motor has been deenergized.

14. The combination with a propeller having a blade, means including a normally stationary shaft for changing the pitch of saidblade during operation of-the propeller, an electric motor for actuating said shaft, speed responsive means for connecting and disconnecting said mining the extent of movement of said first named means and means for drivably connecting said shaft and, control member.

15, In a variable pitch propeller having a plurality of blades, a combined switch and indicating member movable to a'desired pitch setting while the propeller is rotating, and.- electrical means for thereafter varying the pitch of said blades at will, said means including, a switch member coacting with said combined switch and indicating member for automatically discontinuing the operation of said pitch varying means when the pitch of said blades corresponds with the setting of said control member.

16. In a variable pitch propeller the pitch of thereof, means including reductiongearing operable to change the pitch of said blades, an electric motor normally disconnected from said pitch changing means, means for energizing said motor, means responsive to the speed of the motor for drivably connecting said motor and said first named means, and means operated by said motor for automatically deenergizing said motor.

1'7. In combination, a propeller having a plu- V rality Of blades, means including an electric motor for varying the pitch of said blades while the propeller is rotating, means including a pair of relatively movable coacting switch members for energizing said motor, one of said switch members being drivably connected to said motor and operable to automatically deenergize said motor.

18. In combination, a propeller having a plurality of blades, means including an electric morotating, means for thereafter energizing said motor including a second switch member drivably connected with said motor and coacting with said first named switch member, said switch members being so constituted as to deenergize said motor 'when the pitch of the blades corresponds to the setting of the combined member.

'19. In combination, a propeller having a plurality of blades, mechanism including a normally stationary shaft operable to vary the pitch of said blades while the propeller is rotating, an electric motor normally disconnected from said shaft, means for energizing said motor, means for drivably connecting said motor and shaft and means drivably connected with said shaft for indicating the pitch of said blades.

20. In a variable pitch propeller having a plurality of blades, means including a normally stationary shaft operable to vary the pitch of said blades, an electric motor normally disconnected from said shaft, but, adapted when energized to clutch said shaft, means for energizing said motor, means for indicating the pitch of said blades, and means including a differential mechanism for drivably connecting said shaft and indicatin means.

21. In a variable pitch propeller having a plurality of blades rotatable about their axes to vary the pitch, means for so rotating said blades said means including an electric motor, an indicating device movable to a desired pitch setting said device carrying a plurality of contact members, a terminal switch member coacting with the contact members of said indicating device, a

source of electrical energy, a switch adaptedqto gized, means including a pair of relatively mov-.

able coacting switch elements for energizing said motor one of said elements being movable to a desired .pitch setting, means for drivably connecting the other of said elements to said motor said switch elements cooperating to automatically deenergize said motor when the pitch of the blades corresponds with the desired setting.

- 23. A variable pitch propeller comprising a hub, a shaft for rotating said hub, a plurality of bladesrotatably carried by said hub, means for rotating said blades in said hub to vary the pitch said means comprising a pair of spaced worm shafts within said hub, a worm wheel p'ositioned between said worm shafts and cooperating therewith, a'sun gear carried by said worm wheel, a plurality of planetary gears meshing with said sun gear and carried by said blade, a

stationary .internal gear cooperating with said planetary gears and means for rotating said worm shafts while the propeller is rotating to operate said planetary gears to vary the pitch.

24. A'variable pitch propeller comprising a hub, a shaft for rotating said hub, a blade rotatably carried by said hub, means for rotating said blade in said hub while the propeller is rotating comprising a pair of worm shafts within the hub, means including a plurality of planetary Bill memos? gears for clrivalrly connecting said blade and worm shafts, a gear carried in; each oi seiol worm shafts externally of sold into enel meshing with each other endmeens to import rotation to either of selol gears to increase or decrease the pitch of said blade.

25. In a variable pitch propeller, o hub, o pro= peller blade mounted in said hole, means on= ersble for changing the pitch of the loloele in either direction while the propeller" is in opere tion, e. single clutch insole first nomeel nieens encl means opeeohle to disengage seill clutch otter the pitch of the blades has reeehed e nreoetel mined limit in either direction.

, 26. In a verielole pitch propeller, e. huh, e. pro= oeller blade mounted. in said huh, power oner ated means for (changing the pitch of the blade in either direction while the propeller is in on eration, as single rotatable power driven clnteh in said first named means, and means eeerslsle to disengage seiel clutch after the pitch of the blades has reached a predetermined limit in either direction,

27. In a, variable pitch propeller, e. huh, e propeller blade rototabiy mounted in solo huh, power-oneretecl pitch changing mechanism for rotating said blade in the hub to vary the itch while the propeller is in operation, is single clutch in the pitch changing mechanism homolls' en ,gegeci during the pitch changing operation to transmit power to the blades tovery the pitch thereof in either direction, and means operable sites the pitch oi the blades has reaches 9. predetermineo lit ior disengaging sale clutch.

2s. The combination with an airplane driving shaft, oi as proneller huh driven thereby, a, set of it, ole, propeller hob driven thereby, a set of oleoies esrlrieel Toy sold huh and arranged to rotete about their longitudinal axes, means includie. monnsl control for rotsting said blaoles ehensing mesns, s single means operable in one direction for moving solo member to a. desired nitch setting and operable in another direction for initiating oeeretion of said pitchechenging moons, one moons for rendering inoperative sold goitell chengine meenswhen the pitch of said hlelles eorresnonds with the setting of solo control me o I i v SPENCER TH. 

